The Clarion nightsnake, a reptilian species believed lost, has resurfaced in Mexico, a US museum said Monday. Brownish black in color and sporting spots on its head and neck, it was found on the Mexican island of Clarion in the Pacific, some 440 miles (700 kilometers) off the mainland. It was rediscovered by a researcher at the National Museum of Natural History in the US capital, the institution said in a statement.   The snake -- a lone specimen of which is part of the museum's collections -- was first discovered in 1936 by naturalist William Beebe while on an expedition to western Mexico.    While never formally declared extinct, it was struck from the scientific record after scientists were unable to detect any trace of it in the decades that followed, leading them to negate the validity of the original findings, the museum said. Working in collaboration with a researcher from a Mexican institute, Mulcahy carried out an expedition to Clarion island where their team identified 11 snakes that matched Beebe's description. A series of DNA tests confirmed that the Clarion nightsnake is indeed genetically distinct from others found in mainland Mexico. It is now recognized as a full species, according to the museum. "Proper identification is the first step toward conserving this snake, and we plan to continue monitoring this species to learn more about the role it plays in the delicate Clarion Island ecosystem," Mulcahy said in the museum's statement.